This invention relates to a pedal for a bicycle, and more particularly to a pedal for a bicycle, which comprises a a pedal shaft and a pedal body supported rotatably to a crank arm of the bicycle by way of the pedal shaft, so that a cyclist may transmit his treading force to the crank arm for driving the bicycle.
Generally, this kind of pedal is well-known and has a pair of support plates mounted rotatably through balls to the pedal shaft at a regular interval, and a pair of foot plates provided between the support plates and having foot bearing surfaces respectively, or a pedal body with two first and second foot bearing surfaces mounted to the pedal shaft in relation of being displaced with respect to the axis of pedal shaft and supported thereto in cantilever fashion.
The pair of foot bearing surfaces at the conventional pedal are disposed apart from the axis of pedal body at approximately equal distances, whereby a cyclist, when pedalling the bicycle, puts his foot onto the pedal body, contacting at two front portions of his sole with the foot bearing surfaces, and his toes project out from the front foot bearing surface at the pedal body.
Hence, the cyclist, when pedalling using the conventional pedal, tries to apply the treading force to the pedal, but the treading force is not fully utilized due to his toes projecting beyond the foot bearing surface. As a result, the location of the pedal in rotation may not transmit the treading force effectively to the crank arm.
In detail, it is the most preferable that the cyclist, when pedalling, applies his treading force to the pedal body through the foot bearing surfaces in the direction of the tangent to the rotary path of the pedal shaft axis. The foot bearing surfaces at the pedal are usually slant downwardly at an angle of 10.degree. to 15.degree. with respect to the horizon because of the relation of the posture of cyclist pedalling the bicycle with his foot joints, hip joints, knee joints and ankle joints. Hence, the conventional pedal, which has the two foot bearing surfaces at equal intervals from the axis of pedal shaft, is angled at the treading side slightly ahead of the upper dead point of the crank arm in revolution (ahead in the direction of revolution of crank arm when the bicycle is running forward), such that the treading force acting on the foot bearing surfaces through the axis of pedal body is directed considerably slantwise from the tangent to the rotary path of the pedal body axis, and the cyclist cannot effectively apply the treading force to the pedal.
On the other hand, the cyclist will raise the pedal from the lower dead point of the crank arm in the manner of kicking it backward. Since, the cyclist, when using the conventional pedal, cannot apply his treading force to the pedal by his toes, especially the tip of big toe, it is difficult to raise the pedal by use of his toes.